Trigger Shot uses your phone's sensors to trigger camera shots, also known as a External Camera Trigger (ETC).
Included free is the Time Lapse option. This will take pictures based on a time interval.
In the settings you can set which camera to use (rear or front), the picture size, and the flash mode.
Google Drive integration allows all pictures to optionally be uploaded to your Drive automatically.
Pictures will keep being triggered and taken even when the screen turns off. This is save battery power if you want to leave the app running.
Optional modules include: (In App Purchase required)
EMF Trigger - Trigger the camera based on Electro-Magnetic Field values read from the phone's electronic compass sensor. Start and Stop values can be selected.
Vibration Trigger - Take pictures when ever your phone senses vibration above a certain setting.
Light Trigger - Trigger the camera whenever light values change. You can set it so a picture will be taken whenever a light is turned on.
Many more sensor modules will be available shortly.